Printing



W. B. HOWE Dec. 1, 1959 PRINTING I5 Sheets-Sheet 1 Filed July 3, 1956lalrc IIL Inventor Warren .5. 3+owe B3 ZWMW jH-torn eg Dec. 1, 1959 v w.B. HOWE 2,915,006

PRINTING I Filed July 3, 1956 :s Sheets-Sheet 2 Inventor Warren .5.fl'iowe Wa /ace Md Fan/ ow Mk0 rn e g5 Dec. 1, 1959 w. B. HOWE 2,915,006

PRINTING Filed July s, 1956 I I s Sheets-Sheet s Inveni'o r Warren. E.a'fowe Maj/ace Md FM United States Patet O PRINTING Warren B. Howe,Maple Heights, Ohio, assignor to Addressograph-Multigraph Corporation,Wilmington, Del, vand Cleveland, Ohio, a corporation of DelawareApplication July 3, 1956, Serial No. 595,634

3 Claims. (Cl. 101-448) This invention relates to lithographic printing,and in particular to the moistening roller of a lithographic print-.character is then applied to the plate the moistening solution will berestricted to the aforementioned background areas due to theincompatibility between water and oil, and then if a roller bearinglithographic ink is rolled across the plate the ink will adhere to theimage only and will be rejected by the water in the background areas ofthe plate. In most instances, the lithographic printing plate isarranged on a cylinder and is contacted by diametrically composedmoistening and inking rollers. The cylinder which carries the printingplate in turn engages a so-called blanket cylinder, and as the printingcylinder rotates ink applied to the master image is transferred in imageform from the lithographic printing plate onto the blanket of theblanket cylinder, and the sheet to be printed in turn is fed between theblanket cylinder and an opposed pressure or platen roller so that theimage on the blanket cylinder is offset on to the sheet to be printed. t

The delicacy of operation entailed in lithographic printing is of aconsiderable order, and precautions are necessary in order to assure themutually exclusive roles played by the moistening solution and the ink.One of the more important considerations centers about the moisteningrollers in the moisture train of the printing machine which relay themoistening solution to the printing plate. Thus, the ductor roller andthe form roller in this train must be of such nature as to absorb andtransfer relatively large quantities of moistening solution to theprinting plate, thereby bathing the background or hydrophilic areas ofthe printing plate profusely with the moistening solution which keepsthe background areas of the plate free of lithographic ink. In otherwords, assuming in the first instance the development of a sharplydefined master image, the role of the moistening solution is to maintainthis definition. Obviously, if the form roller or ductor roller whichcooperate to transfer moistening solution to the printing plate becomefouled with ink or ink receptive foreign matter there is a tendency forthe ink or the ink receptive foreign matter to be transferred to thebackground areas of the plate which contribute to pickup of lithographicink in the background areas of the plate.

Numerous materials have been tested and tried for fulfilling themoisture absorptivity characteristic of such moistening rollers, and areplaceable molleton cloth cover appears'to afford the most advantageouscharacteristics in ice 2 this regard. But what has heretofore beenentailed is to provide the cloth cover, whatever its specific nature, ofrectangular dimension having a length corresponding to the axialdimension of the moistening roller and a width corresponding to thecircumferential dimension of the moistening roller. The cover is wrappedaround the roller and the longitudinal edges are stitched together.

Covers of this kind have proven to be highly advantageous for impartingabsorptivity to the moistening roller of a lithographic printingmachine, but it has been observed that where the edges are stitched asaforesaid the resulting crevice or ridge tends in some instances to rubthe plate, provide a haven for ink receptive foreign matter, and also tocollect ink from the printing plate with the' consequent disadvantagesmentioned above. While this may not be overly serious or critical undermost conditions, the lithographic printing process is based in the firstinstance upon high fidelity, and the primary object of the presentinvention is to eliminate the need for stitching or otherwise physicallyjoining edges of an absorbent cover on a moistening roller of alithographic printing.

machine. A further object of the present invention is to materiallysimplify the covering of a moistening roller of a lithographic printingmachine and to so cover the roller that no ribs or crevices areproduced.

Specifically, the object of the present invention is to adhesivelysecure and spirally wind an absorbent cover on a moistening roller of alithographic printing machine and to do this in such a way as to produceno apparent rib or. crevice where adjacent convolutes of the cover abut.

Other and further objects of the present invention will i be apparentfrom the following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show preferredembodiments of the present invention and the principles thereof and whatare now considered to be the best mode contemplated for applying theseprinciples. Other embodiments of the invention embodying the sameorequivalent prin-*;

Fig. 2 is a top plan view of the machine shown in Fig. I;

present in- Fig. 3 is a top plan view of a cover of the vention, thisbeing broken away in part;

Fig. 4 is a bottom plan view of the cover'shown in Fig. 3;

Fig. 5 is a top plan view of a cover of larger dimension,

this being broken away in part.

Fig. 6 is a sectional line 66 of Fig. 5;

Fig. 7 is a schematic view showing the way in which a cover inaccordance with the present invention is spirally wound on a moisteningroller; and

Fig. 8 is a detail sectional view showing how adjacent edges of thecover mat together evenly without forming a crevice or ribs.

In Figs. 1 and 2, there is shown the essential structural details of atypical lithographic printing machine simplified in some respects. Aprinting plate 20 is carried in the usual fashion on a printing cylinder21, and the printing plate 20 is adapted to be provided with anink-receptive, planographic master image. Associated with the cylinder21 is a transfer or so-called blanket cylinder 25 provided with arelatively soft, image-receptive blanket 26 on to which lithographic inkin image form is transferred from the printing plate 20 during PatentedDec. 1, 1959 purview of the apview taken substantially on the operationof the machine. Rotatably journalled on a shaft below the transfercylinder'25 is a platen or pressure roller 30, and the sheet to beprinted is fed forwardly along a sheet feed table 31 in to the bight ofthe blanket cylinder and -the -plateh roller 30. Thus, the ink imagethat was transferred to the blanket 26 from the printing plate 20 inturn is offset onto the sheet that is fed between the blanket cylinderand the platen roller. The printing plate has developed thereon a masterimage which isto be repeatedly inked with lithographic ink relayed froman ink reservoir or fountain 35. Disposed in the fountain is a fountainroller 36, and ink is passed from the fountain roller 36 to a transferroller 37 by means of an oscillating ductor roll 38. Ink on the transferroller 37 isthen transferred to the ink form roller- 40 which in turnengages the printing plate.

The moistening solution thatis tobe applied to the background areas of'the printing plate is contained in a moistening fountain provided withafountairiioller 46. Moistening or repellent solution is transferred fromthefoun'tainroller 46 'to the form roller 47' by an' oscillat-ing ductorroller 48, and the form roller 47 engages the printing'plate.

-Under and in accordance with the present invention, the form roller 47and the ductor roller 48 in the moistening train described above areprovided with an absorbent cover wound spirally on the correspondingroller, and this, as will be described below, eliminates the formationof ribs or crevices on the covers of these moistening rollers.

In Figs. 3 and 4 are shown the two sides of the cover 50 that is to bewound on the ductor roller 47, Fig. 3, showing the absorbent face of thecover, and Fig. 4 showing the back or rear face of the cover. In Fig. 5,there is shown the face of the related cover 50A that is to be used onthe larger form roller 47. The absorbent material for both covers 50 and50A in the present instance is a strip or sheet of molleton cloth 51,and this isbacked with an attaching strip in the form of double facedadhesive strip S, Fig. 6, which includes an intermediate sheet 52provided with a film or coating 53 of adhesive on one side and a likeadhesive surface 54 on the opposite or rear side. The adhesive surface53, it will be observed, enables the attaching strip S to be adhereddirectly to the back of the molleton cloth 51. The adhesive surface 54is to be adhered to the moistening roller. Superimposed on the outerside of the adhesive layer 54 is a protective masking sheet 55 thatprotects the adhesive layer 54 until the cover 50 or 50A is" to beattached to the corresponding moistening roller.

Each molleton strip is an inclined parallelogram having parallel sideedges 60, inclined'or beveled parallel end edges 61, and pointed ends'63. The inclined end edge of each molleton strip 51 has a dimension D1which corresponds in length to the circumference of the moisteningroller that is to be covered. The length D2 of the side edge of eachmolleton strip will vary depending in'part upon the length of the rollerto be covered. For a moistening roller 47 or 48 of given axial length Land a given included angle A, Figs. 3 and 5, between adjacent sides and61 of the molleton strip, the dimension D2 will be L/sin A.

As shown particularly in Fig. 4, the adhesive strip S is also aninclined parallelogram and extends from one beveled end edge 61 to theother of the molleton strip so that the long or-side edge dimension ofthe adhesive strip'i's also D2. The adhesive strip, however, is of lessarea than the molleton strip. Thus, the dimension W of each end edge ofthe adhesive strip S is less than the corresponding'dimension D1 of thebeveled or inclined end'edge of the molleton-strip, thereby affordingfree marginal side'fedge' portions E of molleton material outwardlybeyond the longitudinal edges of the adhesive s In winding either theform roller 47 or the ductor roller 48, the masking strip 55 at the backof the related cover 50 or 50A is first peeled off to expose at leastpartially the adhesive layer 54 beginning at a pointed end 63 of thecover. The cover thus having the adhesive layer 54 at least partiallyexposed is juxtaposed relative to the moistening roller to be covered sothat the beveled end edge of the cover having adhesive 54 exposed isaligned accurately with the end face as 70 of the roller as shownin'Fig. 7. Then, while holding and pressing the pointed end portion 63of the cover tightly on'the roller, the loose or dangling portion of thecover is tensioned and wound spirally, that is, helically, in abuttingconvolutes along the length'of the roller while progressively exposingmore and more of the adhesive layer 54 until the opposite beveled endedge 61 of the cover is tightly adhered in alignment with the oppositeend face of the, roller.

The'pitch of the spirally wound cover is determined by the angle A, Fig.3. For a ductor roller as 48 having a circumference of 3%", Iprefer-that the angle A for the cover 50 be approximately 40. For thelarger form roller as 47 having a circumference of 6%", I prefer thatthe angle A for the cover 50A be about 20.

In each instance, the free marginal portion E of molleton cloth strip isapproximately 4;. While winding the cover tightly'on the moisteningroller, the marginal or free portions E of the molleton material ofadjacent cover convolutes 0-1 and 0-2, Figs. 7 and 8, are caused to meshor mat together as shown at E+E in Fig. 8. Such matting together of thefree or overhanging molleton side edge portions produces neither a ribnor a crevice,

and a gap G, Fig. 8, exists between adjacent attaching strip convolutes.

Molleton cloth has a definite nap when brushed or rubbed in onedirection as shown in Fig. 3, and it is important when mounting in themoisture train of the machine a roller having an absorbent outer face ofmolleton wound thereon in accordance with the present invention toassure that the direction of rotation of the roller is opposite to thedirection of the nap or so-called rough grain.

It will be seen from the foregoing, that under the present invention amoistening roller in the moistening train of a lithographic printingmachine can be conveniently and easily provided with an absorbent covermerely by winding the cover on the roller. Thus, no stitching or otherphysical joining of edges of the cover is entailed, and the attachingstrip which is used to hold the cover onthe roller is so dimensionedrelative to the absorbent strip of the cover as to causefree edges ofthe absorbent material to mat together at adjacent convolutes while thecover is being wound spirally on the roller. Accordingly, ridges orcrevices are eliminated from the absorbent cover, thereby greatlyenhancing the ability of the absorbent material to avoid ink pickup orcollection of foreign matter interfering with the essential function ofthe moistening roller which is to relay uncontaminated moistening orrepellent solution to the printing plate-carried by the printingcylinder.

Hence, while'I have illustrated and described the preferred embodimentsof my invention, it is to be understood that these are capable ofvariation and modification,'and I therefore do not wish to be limited tothe precise details set forth, but desire to avail myself of suchchanges and alterations as fall within the purview of the followingclaims.

I claim:

1. In a lithographic printing machine having aprinting cylinderengageable with a blanket cylinder and a pressure roller engageable withthe blanket cylinder, a train. of rollers for transferring liquidtothe.printing cylinder and including a form .roller engageable-with theprinting cylinder, said form roller having an ab;-

sorbent cover v vo'undfhelically thereon successiye convolutes forsubstantially the entire length of the form roller, said covercomprising an absorbent strip affording the outer absorbent surface ofthe cover, and an attaching strip secured to the back of the absorbentstrip, said attaching strip being of less width than the absorbent stripso as to have side edges running parallel to the sde edges of theabsorbent strip but spaced inwardly of the side edges of the absorbentstrip to afford marginal side portions for the absorbent strip free ofand unsecured to the attaching strip substantially for the full lengthof the absorbent strip, and said marginal side portions of the absorbentstrip being matted closely together in edge-eliminating relation wherethe adjacent convolutes abut one another in helical relation along thelength of said form roller.

2. An arrangement according to claim 1 wherein the attaching strip is adouble-faced adhesive strip having one adhesive face adhered to the backof the absorbent strip and another adhesive face adhered to the surfaceof the form roller.

3. In a lithographic printing machine having a printing cylinderengageable with a blanket cylinder and a pressure roller engageable withthe blanket cylinder, means for transferring liquid to the printingcylinder and including at least one liquid transfer roller comprising acylindrical body having an absorbent cover wound helically thereon insuccessive convolutes for substantially the entire length of thecylindrical body, said cover comprising an absorbent strip having a napwith a definite direction and affording the outer absorbent surface ofthe cover, means for rotating said liquid transfer roller in'the machineopposite to the direction of the nap, and an attaching strip secured tothe back of the absorbent strip, said attaching strip including anintermediate sheet having a first adhesive film on one face and a secondadhesive film on the other face, said first adhesive film being adheredto the back of the absorbent strip and said second adhesive film beingadhered to the outer surface of said cylindrical body, and the marginalside portions of the absorbent strip abutting one another substantiallyin helical edge-eliminating relation along the length of saidcylindrical body to afford a substantially continuous, uninterrupted anduniform absorbent surface on said liquid transfer roller.

References Cited in the file of this patent UNITED STATES PATENTS578,958 Webster Mar. 16, 1897 2,633,440 Scholl Mar. 31, 1953 2,647,300Thomas Aug. 4, 1953 2,760,895 Holgerson Aug. 28, 1956 2,763,587 MaslandSept. 18, 1956

